This invention relates to the pelleting of mash. More particularly this invention is a new combination of apparatus and a new method for pre-heating the mash before it is fed to the pellet mill.
There are several advantages to feeding live stock pellets versus the same formula in mash form. In certain feeds, the steam conditioning process prior to pelleting creates chemical changes in the feed making it possible for animals to more rapidly digest and convert the feed to weight. Animals fed pellets are forced to accept every ingredient in the formula, preventing them from picking from the mash only those ingredients they like and rejecting others. Pelleting normally increases the bulk density of mash anywhere from 40% to 100%, thus decreasing the volume of required storage in the same proportion. Many forms of mash, particularly, fluffy feeds molasified or high fat added feeds and urea feeds will hang up in the storage bins. Feeding mash in outdoor lots or bunkers can result in blow-away of substantial percentages of mash. Also, the Federal Drug Administration has recommended pelleting for preventing salmonellosis by killing salmonella possibly present in animal feeds. The destruction of the bacteria occurs from the conditioning process combined with friction heat and pressures of the pelleting process which raise the temperature of the mash and pellets.
Climate affects the pellet quality and output of a pellet mill. In cold climate the temperature of the mash is lower than normal with the result that there is a lower output of the pellet mill. The outside feed bins cause cold product to be batched, and high quantities of steam are necessary for conditioning the product prior to the feeding of the product to the pelleting part of the pellet mill. However, the amount of steam must, of necessity, be limited in order to avoid inefficient operation of the die. Dry heat could be used to condition the product rather than the steam but the costs are prohibitive.
One current method suggested for pre-heating the mash is to divert the mash for the pellet mill feeder and to mix the mash with the warm pellets coming from the pellet mill. After a certain retention time, the combined product is screened, and the pellets conveyed to a cooler and the pre-warmed mash directed to the feeder. Drawbacks are that the screening causes more fines and the pellets have a dusty appearance.